Slice

I recently started learning how to use a slice shot, but my coach told me that there is no point in learning it because the rest of my game is so good. Is it true that learning a slice shot can ruin the rest of your game?

Hell no. Slice is awesome, you just shouldn't use it too much. Slice is very effective at all levels of play- beginners can't handle it, Federer uses it all the time. You just need to know how to use it.

You need to make sure that you hit your slice deep. It makes it difficult to return because it doesn't bounce that high (every player has trouble with low balls). Another advantage it has is that it gives you time to get into the net. So when your opponent hits a weak shot, you're dominating the ball at net.

Use it selectively, on your backhand more than your forehand, and make sure it's deep.